Document Detail

Characterization of glutamine transport in Streptococcus mutans.
MedLine Citation:
PMID:  7567068     Owner:  NLM     Status:  MEDLINE    
Glutamine transport in glucose-energized cells of Streptococcus mutans Ingbritt exhibited Michaelis-Menten-type kinetics with a Vmax of 13.4 nmol/mg dry weight/min and a Kt of 4.1 microM. Diffusion of glutamine into de-energized cells of S. mutans displayed similar type kinetics, with a Kt of 6.8 microM but with a markedly reduced Vmax of 53.9 pmol/mg dry weight/min. Glutamine transport in S. mutans is not proton motive force-driven, as the intracellular accumulation of glutamine by energized cells far exceeded the thermodynamic limits of the proton motive force, and the dissipation of this proton motive force by gramicidin in a high K+ medium did not decrease the intracellular glutamine concentration. Glutamine transport is therefore likely to be energized by ATP hydrolysis. The activity of the transporter was maximal between pH 6.0 and 7.0 and decreased rapidly above pH 7.0. The transport of glutamine was not competitively inhibited by asparagine, glutamate or aspartate, indicating a specific glutamine transport system. Reversed-phase high-pressure liquid chromatography of cell extracts revealed that approximately 26% of the glutamine taken into the cell was converted to glutamate within 10 min. The results are consistent with transported glutamine being converted to glutamate and ammonia by the action of an intracellular glutaminase. Glutamine therefore may be an important source of nitrogen for the cell.
S G Dashper; P F Riley; E C Reynolds
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Oral microbiology and immunology     Volume:  10     ISSN:  0902-0055     ISO Abbreviation:  Oral Microbiol. Immunol.     Publication Date:  1995 Jun 
Date Detail:
Created Date:  1995-11-02     Completed Date:  1995-11-02     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  8707451     Medline TA:  Oral Microbiol Immunol     Country:  DENMARK    
Other Details:
Languages:  eng     Pagination:  183-7     Citation Subset:  D    
Biochemistry and Molecular Biology Unit, School of Dental Science, University of Melbourne, Australia.
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MeSH Terms
ATP-Binding Cassette Transporters
Adenosine Triphosphate / metabolism
Biological Transport, Active / drug effects,  physiology
Glutamates / metabolism
Glutamine / metabolism*
Glycolysis / physiology
Gramicidin / pharmacology
Hydrogen-Ion Concentration
Nitrogen / metabolism
Potassium / pharmacology
Proton Pumps
Proton-Motive Force
Streptococcus mutans / drug effects,  metabolism*
Reg. No./Substance:
0/ATP-Binding Cassette Transporters; 0/Glutamates; 0/Proton Pumps; 1405-97-6/Gramicidin; 50-99-7/Glucose; 56-65-5/Adenosine Triphosphate; 56-85-9/Glutamine; 7440-09-7/Potassium; 7727-37-9/Nitrogen

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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